Vulnerable and non-competent subjects in clinical trials

What is this about?

This page is about participation of vulnerable groups and non-competent subjects in clinical trials. Vulnerable groups include those who could easily be influenced to participate in research, out of fear or pressure. Examples of such groups include soldiers, immigrants or prisoners. Non-competent subjects are those who do not have the legal autonomy to make decisions for themselves, such as children and people suffering from severe mental illness or dementia.

Why is this important?

Throughout history, scientific experiments where often conducted on human beings without their consent, especially during the WW2. Because of that, specific ethical guidelines for human experimentation were developed. One of the ethical milestones in clinical research is informed consent, a process in which researchers ask for a permission before enrolling participants in a trial. The decision to participate has to be well informed and freely given, and without pressure or conflicting interests. This can hardly be achieved with prisoners, soldiers, migrants, etc. Children and patients with severe psychiatric conditions or dementia don’t have the autonomy needed for making an informed decision. These conditions often have specific needs and are of interest in scientific research (specific pediatric or psychiatric diseases), which can raise difficult ethical dilemmas.

For whom is this important?

Ethics committee members, Researchers, Health care professionals

What are the best practices?

Since the WW2, a lot has been said about human experimentation, and particularly vulnerable groups. Many different reports and guidelines were developed and should be consulted before even thinking about clinical research. Start from the Declaration of Helsinki and don’t forget to check regulations of your own country and institution.


1. Hughes J, Hunter D, Sheehan M, Wilkinson S, Wrigley A. European textbook on ethics in research. : Publications Office of the European Union; 2010.

Marin Viđak contributed to this theme.

Latest contribution was May 29, 2019